Lifting mechanism for dump bodies



Sept. 28, 1937.

F. BISZANTZ LIFTING MECHANISM FOR DUMP BODIES Filed Oct. 11, 1955 3 Sheets-Sheet 1 F. BISZANTZ LIFTING MECHANISM FOR DUMP BODIES Sept. 28,

Filed Oct. 11, 1935 3 She'ets-Sheetg 2 .I IIIII IIIIIIIIIIII Sept. 28, 1937. F. BISZANTZ LIFTINI MECHANISM FOR DUMP BODIES Filed 001;. 11, 1935 3 Sheets-Sheet 3 I I II UNITED S TE Patented Sept. 28, 1937 LIFTINGr MECHANISM FOR DUMP BODIES Fred Biszantz, Galion, Ohio, assignor' to The a corporation of Ohio Application October 11,

Galion Metallicvault Company, Galion, Ohio,

1935, Serial No. 44,534

.17 Claims. (01. 298-22) This invention relates to lifting mechanisms for dump trucks, and in particular, to lifting mechanisms having a variable force applied to the dump body and a variable speed. of lift during the dumping operation.

' One object of this invention is to provide a lifting mechanism for dump trucks employing a compound linkage arranged to vary the mechanical advantage of the lifting mechanism smoothly and continuously such that a comparatively large lifting force isapplied' initially to the dumping body at a slow lifting speed, the force being continuously reduced and the speed continuously increased until finally a comparatively smaller lifting force is applied while the dumping body is being lifted at a higher speed.

Another object is to provide such a compound linkage for dump truck lifting mechanism such that the linkage gives the effect of a lever having a smoothly and continuously varying length, being equivalent to a shortlever when the load of the dumping body is heaviest, and equivalent to a long lever when the dumping body is lightest, in its raised position, by 7 reason of its center of gravity shifting to the rear of the truck.

Another object is to provide such a dumping mechanism wherein the compound linkage is so arranged that no dead center exists.

Another object is to provide such a lifting mechanism for dump trucks as to enable the use of a relatively low powered hydraulic unit for applying the lifting force by providing a great leverage at low speed at the start of lifting, the same force serving to lift the load at a higher speed later in the lifting operation.

Another object is to provide a hydraulically operated lifting mechanism for a dump truck such that the hydraulic cylinder is disposed in such a direction that the force exerted by its piston is in the general direction of motion of the dumping body.

Another object is to provide a dump truck lifting mechanism wherein all parts of the lifting mechanism are located and maintained above the frame of the motor truck during the entire lifting operation so that'the same dumping mechanism can be applied to different models and makes of trucks.

Another object is to provide a lifting mechanism for a dump truck employing a compound linkage so arranged that it is equivalent to a variable length lever wherein the distance between the fulcrum of the lever and the point of connection of the lever to the dump body varies greatly, while the distance between the point of application of the force and the fulcrum of the lever remains substantially constant.

In the drawings: a

Figure l is a side elevation, partly broken away, of a portion of a dump truck with the lifting 'mechanism'of this invention, and with the lifting mechanism in its lowered position. 7

Figure 2 is a plan view of the lifting mechanism shown in Figure 1, with the dump body removed to show the underlying mechanism.

Figure 3 is a'fragmentary vertical section along the line 3-3 of Figure 2, showing the details of the lifting mechanism. a Figure 4 is a diagrammatic view, similar to Figure 1, with the lifting mechanism shown at an intermediate stage, and showing the various positions of the'pivots in the compound linkage at different stages in the lifting operation.

Figure 5 is a view similar to Figure 1, but with the lifting mechanism in its raised position. 7

'Figure 6 is a right-hand end elevation of the mechanism shown in Figure 2. 7

In general, the dump'truck lifting mechanism of thisinvention consists of a compound linkage connected at oneend to the frame of the truck and atits other end to thedump body, the lifting force being applied at an intermediate point'by any suitable means, preferably a hydraulic cylinder. The various members of the linkage are so arranged that the linkage acts as a lever Whose length varies continuously and smoothly during the lifting operation. In particular, the compound linkage parts so cooperate with one another that the distance between the fulcrum and the piston connection on the lever remains comparatively unchanged, while the distance between the fulcrum and'the connection of the linkage and the dumping body'in'creases greatly.

- -Hitherto lifting mechanisms have-been provided wherein compound linkages were employed. Certain of 1 these linkages, however, caused the length of the lever to vary abruptly, the point of application of the lifting force being changed from one point to another along the lever as the lifting proceeded. Other mechanisms were provided employing rollers moving along the lever in such a manner that the mechanical ad vantage. applied to the lifting operation varied, but these devices required chains and springs in order to prevent the loss of the body by its tilting backward off the truck during dumping.

In the present invention the compound linkage itself applies a varying mechanical advantage with smooth'rather than abrupt changes, and no such springs or chains are required. Furthermore,

the linkage is of such a nature that a comparatively high lifting force is applied to the dump truck at the start of the lifting operation at a comparatively low speed, and these factors change continuously and smoothly during the lifting operation until at the end of the operation a comparatively low lifting force is being applied to the dump body, the latter moving at a comparatively high speed.

Referring to the drawings in detail, Figures 1 and 2 show'the rear part of a truck having frame portions I. These frame portions I serve to support a supplementary frame consisting of transverse frame members 3 and 4 interconnected by outer longitudinal frame members Zand inner longitudinal frame members 5, (Figure 2). Also supported by the longitudinal frame members are pivot shafts 6 and 1, these pivot shafts serving to pivotally support the lifting mechanism, in a manner hereinafter described. The third pivot shaft 8 is likewise supported by the longitudinal frame members, and carries at each end thereof brackets 9, secured thereto as by the cotter pins ill. Mounted on the brackets 9, as by the bolts H, is the subframe I2 of a dump body l3, supported thereon by means of the cross members I 4. An additional cross member l5, secured to the bottom of the dump body 13 at an intermediate point therealong, supplies a pivotal connection for the lifting mechanism.

The lifting mechanism is connected at one end to spaced pairs of plates I6 (Figure 2), fixedly mounted upon the frame by being supported upon the pivot shafts l and 8. Mounted on the pivot shaft 1 are links l8 having sleeve-like portions I9 providing bearing support therefor. The opposite ends of the links l8 carry the crosshead shaft 20, upon which is mounted the crosshead 2| (Figure 2). Also connected to the crosshead 2| is the piston rod 22, emerging from the hydraulic cylinder 23, the latter supplying the lifting force. The conduits 24 and 25 provide for the admission and discharge of fluid to the lifting cylinder 23. The latter at its rearward end is provided; with a pair of ears 26, pivotally mounted upon the pivot shaft 6 in such a manner that the cylinder 23 may tilt during the lifting operation around the pivot shaft 6.

Also supported on the crosshead shaft 2|] are spaced triangular plates 21, each pair serving as a unit. At one corner of these plates and pivotally mounted on a pivot pin 28 between them is a link 29 pivotally connected at its opposite end to a pivot shaft 30, mounted upon the dump body cross member IS. The remaining corners of the paired triangular members 21 carry a pivot pin 3|. Pivotally supported on this pivot pin 3|, between the plates 21; is :a link 32, the opposite end of which ispivotally anchored on thepivot pin .33 supported between the spaced plates l6.

- In the operation of the lifting mechanism of this invention it will be convenient to show the successive positions of the various pivot axes as the lifting operation proceeds. For this purpose the axis of the crosshead shaft 20 isdesignated as A; that of the pivot pin 3| as B; that of the pivot pin 28 as C; and that of the pivot shaft 30 as D. The axes of the shafts l and 8 are respectively designated E and F.

Referring now to Figure '4, it will be observed that the successive positions of the pivotal axes A, 18,0 and Dare designated by their respective letters followed by the numerals I, 2, 3, 4, 5, 6 or'1, these-representin-g successive stages in the lifting operation. These positions were obtained by adopting a series of positions Al, A2, etc., representing equal angular motions of the link [8 around its pivot axis E.

Thus it will be seen that when pressure fluid is admitted to the hydraulic cylinder 23, the piston rod 22 thereof will be forced outward, causing the cross head 2| to push the crosshead shaft 28 to the right and toward the rear of the truck. This motion causes the triangular plates 2? to be tilted from their lowermost position, of Figure 1, to the intermediate position of Figure 4, and eventually to the final position of Figure 5. In reaching these positions the triangular plates 21 pivot at two points, the pivot points themselves moving in an arcuate path. Thus one corner of each triangle 2"! pivots on the pivot pin 3l which is mounted on the link 32, which in turn, pivots on the pivot pin 33 mounted on the plates [6. At the same time another corner of each triangular plate 21 pivots on the crosshead shaft 20 supported on the ends of the links I3, these in turn, being pivotally supported on the pivot shaft 1. The remaining corner of each triangle applies the lifting force from its pivot pin 28, through the link 29, to the pivot shaft 30 on the dump body cross member [5. By comparing the different positions of the triangular plates 2'! and the links attached thereto, as shown in Figures 1, 4 and 5, it will be seen that the triangular plates 2'! rotate in a clockwise direction while the dump body is being lifted upward.

It will furthermore be seen that the leverage applied to the dump body varies greatly even though a constant force is applied by means of the hydraulic piston 23 and piston rod 22. In the lowest position of the dump body !3 the weight of the contents thereof exerts a dead load in a substantially vertical direction, thus requiring the maximum amount of lifting force to start the lifting operation. As the lifting operation proceeds, however, and the dump body is tilted around the pivot shaft 8, the center of gravity of the load moves toward the rear and more nearly over the pivot shaft 8. As this occurs less lifting force is required and a higher speed of lifting may be accomplished with the same lifting force. As a result the lifting force applied by the piston rod 22 exerts a great mechanical advantage at the start, and applies a comparatively large lifting power to the dump truck body because the distance between the fulcrum shaft '1 with the axis E and the axis D of the pivot shaft 353 is relatively small, and almost as short as the distance between the axis E of the fulcrum or pivot shaft l to the axis A of the crosshead shaft 20. The latter distance, however, remains substantially constant during the lifting operation, whereas the former distance increases enormously, as shown in Figure 4. In particular, the distances AlE and A'lE are constant and of equal radii, whereas the distance D'l'-E is several times the distance Dl--E.

Translated into terms of mechanics it will be seen that as the lifting proceeds the force arm of the equivalent lever, which is the distance between the point of application of the lifting force and the fulcrum, remains substantially unchanged, whereas the weight arm, which is the distance between the fulcrum E and the point of application D'of the lifting power, increases greatly. As the actual force applied to the crosshead shaft 25 varies somewhat, due to the different angular relationships between the piston rod 22 and the link It, the leverage exerted thereby will vary somewhat. At the same time, however, the leverage applied by reason of the lengthening of the weight arm of thelever, due to the increasing distance between the axes E and D of the pivot shafts I and 3|], causes the actual lifting force applied to "the dumping body to be continuously reduced and the lifting speed'continuously increased as the bodymoves upward toward its raised position.

By reason of this construction a comparatively small hydraulic cylinder 23 can be employed, and the oil pressures therein kept very low so that the resulting strains on the entire structure are not severe at any time. The smooth and continuous change in the power applied to the dumping body, through the construction of the linkage of this invention, results in an absence of abrupt changes in the oil pressure because the lever lengthens continuously and not in abruptly changing stages,

as in the prior art. The dump body in its lowest position thusstarts tilting'at a slow speedand finishes at a rapid speed, with very little change in the oil pressures in the hydraulic cylinder 23.

I desire to comprehend within my invention suchmodifications as may be embraced within my claims and the scope of my invention.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In a dumping truck, a frame, a dumping body tiltably mounted on said frame, a source of lifting force, a link pivotally mounted on said rame and operatively connected to said source, a member pivotally connected to the swinging end of said link at one point, a second link pivotally mounted on said frame and pivotally connected on its swinging portion to said member at another point, and a third link pivotally interconnecting said member at a third point on the same and to said dumping body.

2. 'In a dumping truck, a frame, a dumping body tiltably mounted on saidframe, a source of lifting force, a link pivotally mounted on said frame and operatively connected to said source, a member having a plurality of pivotal connections thereon, said link engaging said member at one of said connections, a second link pivotally mounted on said frame engaging said member at another of said pivotal connections, and means interconnecting still another pivotal connection with said dumping body.

3. In a dumping truck, a frame, a dumping body tiltably mounted on said frame, a source of lifting force, a link pivotally mounted on said frame and operatively connected to said source, a member having a plurality of pivotal connections thereon, said link engaging said member at one of said connections, a second link pivotally mounted on said frame engaging said member at another of said pivotal connections at a point spaced apart from the frame mounting of said link, and means interconnecting still another pivotal connection with said dumping body.

4. In a dumping truck, a frame, a dumping body tiltably mounted on said frame, a source of r lifting force, a link pivotally mounted on said frame and operatively connected to said source, a member having three pivot points, said link engaging said member at one of said pivot points, a

second link interconnecting another of said pivot points with said frame, and a third link interconnecting the third pivot point and said dumping body.

5. In a dumping truck, a frame, a dumping body tiltably mounted on said frame, a source of lifting force, a link pivotally mounted on said frame and operatively connected to said source,

a :member havingntriangularly disposed pivot points, said link pivotally engaging said member at one of said pivot points, a second link connected at one end to said second pivot point and at itsotherendito 'saidframe, and means pivotally interconnecting said third pivot point and said dumping body. 1 1

6. In a dumping truck, a frame, a dumping bodytiltably mounted on said frame, a lifting motor movably mounted on said frame, a. link pivotally mounted on said frame and connected to said motor, a member with spaced vpivot points mountedonsaid link, a second link pivotally'interconnecting'one of said pivot points andsaid frame, andzmeans interconnecting a third pivot point and said dumping body.

z, "7., In a dumpingtruck,xa frame, a dumping 'bodytiltably mountedon said frame, a lifting motor, movably mounted on said frame, a cross,- head on'said motor, a plurality of links pivotally interconnecting said'crosshead and said frame at .substantially 'coaxial pivotal connections, a plurality of 'members with triangularly disposed pivot points mounted on saidlinks, and means interconnecting the .pivot points remote from pivot points mounted on said links at points substantiallyaligned with the .pointsof pivotal connection thereofwith said 'crosshead, and means interconnecting the pivot'points remote from said link connections with said-frame and said dumping body respectively.

9. Ina dumping truck, aframe, a dumping body tiltably mounted on said frame, a source of lifting force, a link pivotally mounted on said frame and operatively connected to said source, a member with spaced pivot points mounted on said link, a support on said frame, a second link interconnecting said member with said support, and means interconnecting said member with said dumping body.

10. In a dumping truck, a frame, a dumping body tiltably mounted on said frame, a source of lifting force, a link pivotally mounted on said frame and. operatively connected to said source, a member with spaced pivot points mounted on said link, a support on said frame having a pivot point, a second link pivotally interconnecting a second pivot point on said member with the pivot point on said support, and a third link pivotally interconnecting a third pivot point on said member with said dumping body.

11. In a dumping truck, a frame, a dumping body tiltably mounted on said frame, a source of lifting force, a link pivotally mounted on said frame and operatively connected to said source, a member with spaced pivot points mounted on said link, a support on said frame, a second link interconnecting said member with said support, said second link being shorter than said first link between the pivot points thereof, and means interconnecting said member with said dumping body.

12. In a dumping truck, a frame, a dumping body tiltably mounted on said frame, a pair of links pivotally mounted on said frame at spaced intervals one above the other, a swinging member pivotally mounted at spaced points on the swinging ends of said links, a source of lifting force connected to said swinging member, and link means interconnecting said swinging member and said dumping body.

13. In a dumping truck, a frame, a dumping body tiltably mounted on said frame, a pair of links pivotally mounted on said frame, at spaced intervals one above the other, a swinging member pivotally mounted at spaced points on the swinging ends of said links, a source of lifting force connected to said swinging member, and link means interconnecting said swinging member and said dumping body, one of said links being shorter between its pivots than the other link, each of said links being movable relative to each other.

14. In a dumping truck, a frame, a dump body pivotally mounted on the frame adjacent the rear end thereof, elevating power means for supplying power to elevate said dump body, a pair of links pivotally .attached to the frame forwardly of the point of pivoting of the body, an intermediate member pivotally connected at one point to one of said links and at another point to the other of said links, and means pivotally connecting said intermediate member with said dump body, said links being pivotally anchored to the frame at points remote from each other and from the axis of pivoting of the body on the frame.

15. In a dumping truck, a frame, a dumping body pivotally mounted on the rear end of the frame, an elevating plunger pivotally mounted on the frame in the plane of the mounting of the body but forwardly thereof; a connecting means pivotally connected .to the elevating means; and links pivotally connecting the connecting means to the body and to the frame, the pivotal connection of the link to the frame and the connecting means being on the same center as the connection of the elevating means to the connecting means; and means to connect the connecting means pivotally to the frame on a pivotal center remote from the frame.

16. In a dumping truck, a frame, a dumping body pivotally mounted on the rear end of the frame, an elevating plunger pivotally mounted on the frame in the plane of the mounting of the body but forwardly thereof; a connecting means pivotally connected to the elevating means; and links pivotally connecting the connecting means to the body and to the frame, the pivotal connection of the link to the frame and the connecting means being on the same center as the connection of the elevating means to the connecting means; and means to connect the connecting means pivotally to the frame on a pivotal center remote from the frame, said connecting means comprising a triangular plate, the base of which is diagonally disposed upwardly when the body is in its lowered position and is horizontally and downwardly disposed when the body is in its elevated position.

17. In combination, in a dump truck, a frame, a dump body pivoted on the rear end of the frame, a piston rod elevating means pivotally connected on the frame forwardly of the dump body pivoted end in the plane thereof, a link means pivoted to the frame intermediate the aforementioned pivots having its free end connected to the end of the piston rod elevating means, a plate connecting means also pivotally mounted on said connection, link means connected to said connecting'means'at one end and to a point on said frame out of alignment with the pivotal connections of the body and the elevating means on the frame, and a third link means connected to the connecting means and the dump body, whereby as the body is elevated the connecting means rotates on its pivotal connections and elevates.

FRED BISZANTZ. 

